Separation anxiety maybe?

I don't have a clue what's happening... but I'm so tired, this has been happening for probably over a month now... My little one was poorly with RSV beginning of September, and as he has had it before we didn't take him to a&e unless we really had to, so I co slept with him, my anxiety was all over the place and I couldn't sleep probably. Since then he's better. But he screams in the middle of the night so high pitched it's crazy, but the second I walk in the door he stops lays down and goes straight back to sleep. Then I'll leave once he's fully asleep but the minute he realises I'm gone, he will stand straight back up, high pitch screen until I come back and sit with him... What is happening? I'm so tired it's 3:18 right now and he's had me up twice since 2am 😩😩😩