Son didn't wish me a happy birthday and went off on me

Yesterday was my birthday and I waited for my son to call me to wish me a happy birthday and he never did. He's 16 and living with his dad and his dad girlfriend. He is on the autism spectrum and just got diagnosed last month with bipolar l. He just got out of mania over a week ago so I wasn't trying to be too hard. I just called him to let him know he forgot. He answered the phone with a WHAT! and I told him to watch the attitude. I told him my birthday was yesterday and I didn't even get a call. He said he forgot and was busy with stuff. I just tried to tell him how much it hurt me because I remember his birthday all the time and he got mad, told me I'm stressing him out and told me to fuck off and I guess threw the phone because I heard it crash. Then I heard his dad yell at him and say "Go take you goddamn medication! Fuck!" His dad answered me. Told me it's not a good time and he's been dealing with this all week and the medication switch isn't helping. Then hung up .. well fuck me I guess... I just wanted a little mama appreciation.