Sure sounds like brumation to me. We fell for that one too. Judging by ours, the first year, they don't really seem to brumate much, then the second year they do more their normal pattern. When ours was two, we became quite concerned in the fall when he did nothing but sleep all the time. We knew about brumation, but just didn't understand it could be as extreme for some as it as for ours, especially since we had had to deal with coccidia before and were concerned it had returned. We took him to the vet, got special food that we woke him up for everyday and feed him with a dropper, spent a fortune, etc. Then by the next year, we learned. We just happen to have a deep brumater. Ours goes to sleep like a rock about the beginning of September every year and sleeps rock solid until about New Year's, then he is unstoppable for several weeks being quite hyperactive and eating everything in sight. He's about 5 now and we have learned that this is "just him" and know to expect it. I think it would be easier to recognize as brumation if they did it on a schedule you would expect, like say December to March, but they seem to march to their own clock. We were quite surprised to finally realize ours seems to think the days getting shorter even in late summer means it's time to go to sleep and days getting longer, even in December means it's time to wake up. Best of luck with yours.