My platelet count was 172 a year ago, and now 144. i also have had night sweats on occasion for the last year or two. should i be worried?

Platelets are OK: Platelet counts tend to flucctuate over a wide range. So you do not need to worry about your counts unless the value is close to 100,000 or lower. But why are you getting your platelet count checked? Tests done without a good reason can mislead you and get you into more trouble that you may realize, so avoid testing unless there is a good reason, suspected problem which can be resolved by the test