I Have Been Noticing That I Am Having Memory Gaps

I have been noticing that i am having memory gaps and difficulty processing work duties that I have understood and functioned well in for a few years, my employer has noticed and I am seeing my dr in a day or two. My employer asked me to consider going on a medical leave as they are concerned for my health. I had a blood clot in 1983 during pregnancy, TIA Jan 1998, and recently (5 months ago) had a sudden onset of Periconditis with really high bp and chest pain and given antiflammatories and pain killers...my ability to function (I work at a bank) has deteriorated, I am making errors that I'm not even aware I'm making, as Im certain I've done the right thing, and yet when my employer shows me what I did, I am shocked. I have no recall of the event or how I could've possibly done such a thing. This has alarmed me. I'm on zoplicone and thyroid meds and mentioned to dr prior to my work asking me to go off on medical, if perhaps i'm reacting to those things...we are investigating...could I be having TIA's...there are times when someone is speaking to me that I cannot fully grasp or retain what they are telling me. It's quite embarrassing. What is happening to me? I am a 55yr female.