My son is 4yr and won't let me out if his sight?

My son is 4 yr old and will be 5 in sept and he has been for the most part sorry bout the bluntness but stuck up my butt. If he is in the playroom which is rite off my living room and i go to the bathroom he will scream and cry like someones killing him if he's playing i'll tell my 7yr old i'm switching laundry my 4 yr old will flip as soon as he realizes i left the room. I tried telling him i'll be rite back i'm going potty or i'm switching laundry he has to follow me i don't mind him switching laundry with me but he's getting a little big to follow me to the bathroom. I can't go into the kitchen to even poor a drink without telling him so he can follow or he freaks out. He also sleeps in my bed me and my husband will take him back to his room 50x a night but he screams and wakes up my 7yr old which he shares a room with. I'm mainly concerned because I am 8m preg and he insists he's staying at the hospital with me. My mom has taken him over night to give me a break and she said he cries 90% of the time and is up most of the night. I don't send him alone so he is not completely by himself there my 7yr old and 2yr old go with him. Also he starts school in sept full day I really would appreciate some advice. Thank you