You need an in-person medical evaluation. Generally, the drill is an x-ray film and they insect a trochar (needle) to extract fluid. They are looking for blood. The idea is to "rule out torn miniscus". An MRI is definitive. The good news is that often simply withdrawing fluid will relieve all symptoms. The procedure is relatively painless, but there is a big needle so close your eyes and look away. If there is miniscus damage, you need to determine how bad the damage is.
You make an appointment to see your doctor, who will examine the knee and will probably send you for an xray or an ultrasound scan (or MRI) depending on what the doctor decides may be the cause.
You will also need a referral to a physiotherapist to give you specific exercises to do on the knee.
Doesn't sound good with you "cracking" your knees in the morning.
Forget about different procedures at the moment. You need to get the correct diagnosis urgently to find out what the problem is before worrying about what procedure you will be referred to have.
In the meantime, put a cold compress around the knee and keep any weight off the leg. Elevate the leg as much as you can.
If you felt the problem straight after your game of rugby, I suggest to get someone to take you to the Emergency Room in the hospital, they will examine the knee and take an xray to see if there is any bone damage.
In the UK you have to go within 24 hours after an injury otherwise any later than that you need a referral for imaging by your doctor.
Get someone to take you to the hospital ER urgently.
Let me know how you get on.