The doctor doesn't have reasons. They have all the knowledge there are years of proofs with their chronic illness. The doctor wants to run tests that have already been done multiple times so they can bill health insurance. The prednisone works.

When I was on it, I was having basically roid rage. Anything could set me off and I would get super pissed. I had tons of energy and didn't sleep much. I was glad to finally be off of it.

Seconding this. Prednisone is a very effective immunosuppresant. This is very helpful if you're experiencing a severe immune overreaction (e.g. I once had such severe tonsil swelling that I didnt sleep for three days because anytime I nodded off I'd immediately choke on my own spit), but the side effects are major. Minor colds will knock you flat on your ass, anything worse will hospitalize you, and you'll have food cravings like you're preggers.

Go to the doctor, explain the symptoms clearly, and weigh the tradeoffs.

Prednisone can be a (literal) lifesaver, but its risks are no joke.