Have you had central heating on or some kind of heat source ie electric fire, range, log burner etc this can cause fatigue ie environment temp internal body temperature. Autumn is best time of yr for me not hot not cold (at the risk of sounding like Goldilocks ‘just right’) ie layers of clothing, not cold enough for heating not warm enough for fans - stayed at friends recently who had programmed heating to come on hour before pers woke up cut to me waking up into fatigue and using coffee to get past it but when the caffeine runs out and the heating is still on back comes the fatigue. After a really really long & boring ramble ☝️🫣😬 sorry - maybe do a diary to occupational therapists always suggest this to identify patterns, triggers then you can avoid or think of strategies to compensate ie painkillers 30mins later fatigue nap. Heating on - fatigue due to heat airless/environment , heating off fatigue due to cold remedy heating on for hour 2/3times per day only. Hope you feel better soon & this helps in some way 🤞🍀👍✊🫂 take care & good luck