This has happen a couple times with us.
1st-Lo bumped his head in tub and wanted out right away, I took him out, and once he was calm put him back in, he wasn't having it but forgot next day.
2nd-When i introduced a bathring, he did not like, but as soon as I jumped in with him he was fine.
I agree with sjeb, shower could be away to start it back out and then eventually try bath again.
I don't think I would keep putting lo in tub incase he is scared of something, try shower or spung baths for awhile, and then try tub again.
Hope everything works out