Is there any reason why right flank pain would be much worse when sleeping or lying down? no gi or ut symptoms. is it more likely muscle-skeletal?

Discuss with your MD: Your difficulties can not really be helped without more information, your doctor will start with a good interview and examination, than maybe some testing of lab work and/or imaging. Urinary issues can present like this without typical urinary complaints. There are too many possibilities to cover in this forum. Best wishes.