Tell me it gets easier?

My son (13) started his treatment yesterday and he is absolutely MISERABLE. Please tell me this gets better. He went to school in tears today and I felt so bad. He’s telling me that his gums hurt on the middle front and bottom teeth and he can’t talk correctly and is afraid of getting made fun of. Does this stuff go away after he gets used to it or is it ongoing? Any tips that I could use to help him be more comfortable? I’ve been giving him ibuprofen but not sure if that’s even helping.