Do doctors have to meet a prescription drug quota?

I am 28 and was diagnosed with Ulcerative Colitis a few years back. Since that time, doctor's have been pushing me to take very expensive drugs even when I am feeling good. They are all saying "Okay, this is your condition, take this drug and get out of here". Very little thought seems to go into choosing which drug I need, or if I need them at all. Usually these drugs have made me sicker than I should be.
It makes me wonder if they have prescription drug sales people that are pressuring them into writing prescriptions so that they can make more money.