I have had and still have some of the things you mentioned, eye floaters, fatigue etc so yes it could be lyme and/or co-infections. As Jackie said find an LLMD since this is too complicated for a regular doctor.
Greetings. Sorry you aren't feeling well. More details below, but here's the short answer:
===>>> You really need to see a Lyme doctor as soon as possible -- no more do-it-yourself diagnosis, or treatments by docs who are not Lyme specialists.
'Lyme' is a complex infection that about half the time come along with other infections (as a group, these bonus diseases are called 'co-infections'). I am not medically trained, nor is anyone here that I know of, so below is just what I've read on the internet and learned from having Lyme myself.
Many MDs do not take Lyme seriously or understand that the 'Lyme' ticks and any of the half-dozen possible co-infections need separate testing, diagnosis and treatment.
It's not clear from your post that the MD you first saw ("the doc there gave me Ceftin for 10 days") knows how to deal properly with Lyme. I just searched briefly online for -- "lyme disease" ceftin -- and ceftin did not show up as useful in Lyme. If that's the case, then you need to see a real Lyme specialist. Not all antibiotics are created equal, and a Lyme doc would know that. The doc you saw seems to be going by an old playbook. That way lies trouble in my experience. (It took me 20 MDs before one of them finally tested me for Lyme ... which came back positive, but Dr #20 shrugged and said I wasn't sick enough to have Lyme. Actually, it was worth than that: the doc said, "I would say you have Lyme disease, but I have patients with Lyme disease ... and they are all ... near death." And because I wasn't picking out a coffin yet, this otherwise well-educated and careful MD told me I did not have Lyme, and goodbye. That's how bad it is out there in Medical World.)
Why did you start to feel better after a while? Perhaps because Lyme symptoms come and go in waves as the bacteria reproduce and send out new baby Lyme bacteria to make you feel lousier again. Everyone is different in these reactions, so don't rely heavily on a symptom checklist approach, and partly because any co-infections bring their own special co-infections. You say, 'Just recently some of the symptoms and new ones ... are coming back and getting worse.' That's typical. I felt like I had a combination of a hangover and the flu, 24/7, but everyone's symptoms are different, so don't try to match up too closely with what you read or hear. That's the doc's job.
I'm not medically trained, but I'd be concerned that the treatment you have gotten already did not cure you and may not be effective even with more dosing of the same meds. Lyme needs specific meds depending on what infections and co-infections you may have, and a Lyme doc would know what. Waves of feeling worse often come every few weeks, but don't rely on a calendar to say that your symptoms returning in [20] days instead of [10] days means the infection is not Lyme. Lyme is tricky and sneaky, and co-infections (which have their own rhythms) will come and go at will.
Eye floaters, muscle fatigue, soreness, and tingling are all consistent with Lyme, from what I read. Eye docs (that is, MDs who specialize in eyes, meaning ophthalmologists) are quite aware of the problems with Lyme, and you and your new doc may wish to have you consult with an ophthalmologist just to be on the safe side. Not all Lyme docs suggest that, but mine did, and I was fine, but it gave me comfort that things were okay. Losing my eyesight is not on my wish list.
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My uneducated guess: The antibiotics you took may have set the bacteria back a bit, but didn't kill them off, and neither did your doc.
Without any hesitation at all, I would, in your situation, get myself to a Lyme specialist. If there is no Lyme doc near you that you are aware of, go online and search "LLMD Omaha" or wherever you are near, and also go to the ILADS website and request a referral to a Lyme doc near you. If you have to drive a ways to see a good Lyme doc, it's worthwhile. Once established with an LLMD, follow up appointments are often just once a month (for months, and up to ~a year perhaps) to monitor your meds and your progress.
And you must promise not to freelance with antibiotics, okay? That way lies trouble in a big way. Your first doc meant well, but appears not to know beans about Lyme, in my non-medical view.
Let us know how we can help. Lyme can be beaten, so go for it! Keep us posted.