My Body Is Not Used To Taking Medication And I

My body is not used to taking medication and I just had a aortic valve replaced? through the groin. However I was told the Heart was disabled during that procedure and I now have a pacemaker. I have been on all kinds of medication which I believe has been a shock to my system. I am on clopidogrel and I read that it can affect the Urine output and I should get immediate help but the doctors don't seem concerned about this. My urine output has drastically been reduced and I have swelling of my calves and ankles.Is there any other medication I can take to help prevent blood clots? What should I do? I am in a panic thinking eventually I will need dialysis.