Can only have bowel movement in the morning after drinking coffee.. what can cause this? stool comes out skinnier and longer than normal sometimes.

Change in bowels: Change in bowels is a red-flag to doctors-- this includes alteration in stool texture, altered ease or completeness of elimination, frequency of stooling, occult bleeding, etc. Risk factors, co-morbidities, changes in activity/stress/diet, metabolic factors (diabetes, low thyroid) must be considered. It may be nothing serious, but medical evaluation is recommended & will likely prove reassuring.