Had kidney stone removed week ago. Stent for 3 days. After removal extreme bladder spasms at night. Should I be worried, can it be another stone?

Don't worry (yet) It is very common to have spasms after placement and removal of a ureteral stent. If the pain does not resolve after 2 weeks consider seeing your urologist and maybe even getting another ct scan to look for additional stones.
Stents. It's not uncommon for ureteral spasms to occur for several days following removal of the ureteral stent. Is also remotely possible that an additional stone has dropped into the ureter is creating ureteral colic.
No worries yet. Bladder spasms are common after stent removal but so are additional stones. If the pain isn't improving please see your urologist. .