Is it true that during fall and winters, tsh rises again. do i need a higher dose of synthroid (thyroxine) from oct?

Unlikely: I have never heard of this occurring and have not noticed it in my patients despite 30+ years of practicing. If your TSH level has been fluctuating, the most likely cause is that you should be taking a brand name form of thyroid hormone (Synthroid, Levoxyl, (thyroxine) Unithroid, etc), take it on an empty stomach and wait 60 min before eating. No vitamins or supplements until at least 4 hrs later.