Almost every basic training unit is an infnatry unit. It does not mean he was transferred into the Infnatry. In AIT, he will be in another unit. They probably would not give him medication for insomnia, or any other permanent condition requiring permanent treatemnt, unless they determined that he absolutely needed it, and then only if they were going to put him out. He should have contacted you and given you a mailing address, and called you once he got to his basic training company. If he didn't, it is probably because he dialed the wrong number, or you weren't home, or he was stupid and called his girlfriend or something. When I went in, they required us to write a letter the first day to our parents too. They made you give them a letter to mail. You did not have a choice. You should be getting a letter in a few days with his mailign address. He will also eventually (after the first few days) be allowed an hour to get his personal things cleaned and organized, read, and/or write letters. I never wrote, but hopefully he will drop you a letter in a week or so. If not, you can call Fort Knox, and eventually get the number for his basic training company or Battallion, and they will give you his address and tell him to write you a letter, and will, if you actually get ahold of his company, let you know that he is allright. If you do that, though, he will get in a bit of trouble for not writing you or calling you.