how do u heat ur tank?? if u have just a light over top u may want to start looking into under tank heaters (UTH) and a thermostat. but ur temps do seem good, i wouldnt worry unless they get below 75 for a few hours or so.
offer frozen thawed and if he doesnt take it just leave it in the warm hide over night. most times they will eat it by morning. if not just throw it away and do it again on the next feeding day. i do this all the time and it works. he may not be eating cuz of the time of year, it being 6 yrs old its prolly wanting to breed.