Carotid doppler symptoms and conditions

Gosh, I just got on the internet to see if some of my husband's symptoms (dizziness, muscle cramps, depression, feeling tired and short of breath all the time) could be caused by his medication. Now I'm really worried after reading all the other posts about Lisinopril. We've been trying to get something done about his symptoms for weeks now and not once has a doctor mentioned that it could be the Lisinopril or even checked his potassium levels or done an EKG. We have been told by a doctor who practices in another state that a carotid doppler should have also been done but if we ask for that, we are concerned the doctor will think we're trying to tell him/her how to do their job and then we won't get anything done. I'm afraid to take him off the Lisinopril 20mg suddenly.