Cough which after several months subsided but my knees crack when...

I would suggest you have the doc prescribe a different blood pressure medicine. Lisinopril is an ACE inhibitor and those are known to cause a persistent dry cough as a side effect although that usually comes with long-term use or high doses. I don't know about the knees cracking, never heard that one before but if you have noticed that it happens only when you take the lisinopril then trust your instinct and be persistent with your doctor. Sometimes you just have to insist that you want to try something else. If the doc refuses to listen to you, then your alternative is to seek another opinion.
Clarissa