Hope you are doing good.

Your category change from OBC to general during online document verification. This is probably because the concerning authorities have rejected your OBC caste certificate or maybe it's due to a small technical Glitch. It happens sometime.

It happens sometime you don't need to worry.

I would advise you to immediately write a email to the concerning authorities. Mention your problem in detail and if they don't reply in a single email try writing to them 3-4 times.

Write an email to the official website and they would be able to help you.