It sounds, to me, like you may have some type of pelvic infection, such as Pelvic Inflammatory Disease. Especially if you've been having more frequent intercourse, or have stopped using condoms regularly if you used them before you began trying to conceive, you may have gotten an infection which has spread to your pelvic organs. It could be/have been just a yeast infection or bacterial vaginosis, not necessarily a sexually transmitted disease (hopefully your partner is faithful, which is why I mentioned the others first). PID can lead to fertility problems.
The other concerns I think of... which I hate to even say, especially as a stranger online... is that you are pregnant but it's a tubal pregnancy, or you're having a miscarriage.
Because of the tubal pregnancy possibility-- which is a strong one, not just a little guess, although I'm certainly not a doctor-- you should call the gynecologist's office Now. Call even if they're closed, to speak with the on-call doctor. I'm pretty sure they'll either want you to come in immediately or go to the Emergency Room. The doctor can help you get help in the ER faster than usual, if that's what they suggest. If for some insane reason the gynecologist doesn't take you seriously, call your primary care doctor. Or just go to the ER and call from there. Honestly, if I were you, I'd go straight to the ER. A tubal pregnancy can cause fertility problems and even be fatal-- and suddenly, not slowly. I'm so so sorry I keep saying scary, awful things. I just don't want you to get sicker.
I hope it's something minor-- but if I didn't mention the other possibilities and you got sicker, I'd feel absolutely awful. Whatever is happening, I hope you feel better very soon and go on to have as many healthy babies as you want to!
Sometimes periods can be irregular but since you are having painful bleeding, hence the possibilities of an abortion and endometriosis should be ruled out. You can confirm it by getting your HCG levels checked.In case of pregnancy loss,the value of HCG will return to a non-pregnant range(<5 mIU /L) about 4 - 6 weeks after a pregnancy loss.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.