Your description of the "loop" and "reset" phenomenon describes my second and last LSD experience. I've never heard anyone else describe this effect on LSD.

The first experience was very positive, fun, and visual. The second many years later ended with a repeating short period of slowly descending into darkness with associated very bad feelings terminating in something that felt like death.

Then the descent would end suddenly as if by a stroke of a magic wand and we were magically and instantly back into a feeling of complete bliss that slowly started slipping away again. This happened over and over again like a roller coaster ride.

The hits were blotter with a clown's face and sold between two Rocky Rococo Pizza fridge magnets. I'll never forget that because I always theorized the magnets had negatively affected the molecules of LSD. :)