What Causes Drop In Platelet Count With History Of Hashimoto's?

i have had hashimotos since 3005, i've also had slapingo-oophorectomy. back then i had probloms with low hemoglobin, but my platelet count was normal. in 209 my platelet count had drooped to 101,000. then Nov of last year i had unexplained high temp when CBC was done my platelet count had dropped to 81,000, the physichian told me to take Ferli_6 one tab per day-that didn't seem to help coz it dropped to 71,000 within 2 weeks. then it seemed to get better. in jan my family doctor told me to take 2 Ferli per day n bt the 23rd the platelet count had increasd to 82,000. then on the 16th i had another bout with high temp another cbc was taken n it showed a drop of platelet to 65,000(all in 20 days). should i worry?