Need help: My son will be 2 in 3 weeks. Lately he has been whining ALOT. He will be playing with his…

Need help: My son will be 2 in 3 weeks. Lately he has been whining ALOT. He will be playing with his toys or just walking around and will just randomly start whining and when you ask him what’s wrong he just keeps whining. He has clean diaper on, cup of milk and has ate but will still whine. I comfort him, I ask him what’s wrong but I’m not sure what’s going on. He doesn’t have a fever or anything. Just wondered if anyone else has gone through this and if it was normal. What do you do about it