How can they arrest my son for something he already served time for?

My adult son, who doesn't reside with me, was doing weekends in a jail as a result of driving with a suspended license. He missed 2 weekends and when he went in for his next weekend they kept him to finish the sentence consecutively. They added a few days. He got out and now almost 2 months later 6 sheriffs show up at my home and tell me they have a warrent for his arrest due to skipping 2 weekends. The warrant was obtained the same day he went in and they kept him. They came to my home, said I had to let them in to search for him. They came in and made my youngest son get out of bed and sit on the sofa. They took the keys to an upstairs room I use for storage and searched it. They wouldn't allow me to follow the police in my own home. Is any of this legal?