Seperation Anxiety?

Bedtime = hell
This is not even an exaggeration either. About 2 weeks ago, Zachary decided that bedtime was the devil. It breaks my heart so bad when bed time comes along. We take him upstairs, and brush his teeth, then as soon as we are done - he knows. The hysterical crying begins and the screams. And I'm not talking about regular screams, I'm talking about screams like the child is being attacked! I feel like we have tried everything too. We try our best to calm him down before, but it never happens. We have tried moving his bed time, changing our routine, watching TV in mommy and daddy's bed before - everything - nothing is working. After I have left the room, the horrific cries continue for about 20min. I hate it. It has gotten to the point that I am ready to call the doctor to get some suggestions from him.
My friends have been great, giving me their input on possible ideas. The unfortunate part? We have pretty much tried all of their ideas, except for the book recommendations. Guess that is next.
I really am stuck - I have no idea what to do next. He used to be so good at bed time - then, all of a sudden, this started.
It is only bedtime though - nap time is good. He does his normal cries for the 'I'm not tired' routine, but falls to sleep pretty fast. I always knew that bedtime would be hard, but I just don't know how to handle this. I hate hearing my child cry for me.
I am starting to think that he is having separation issues. He has woken up a couple times in the middle of the night, can't console himself, and we have to go in there. He squeezes so hard, you have trouble breathing! But recently, leaving him at daycare. When I pick him up, he doesn't want to leave, but when i try to leave in the morning, hysterics! Not so much for Jason, maybe because he is more accustomed to daddy's schedule of coming and going, and expects me to be there more often, I don't know. We talk about what we are going to do that day in the car, so he is prepared, we get to daycare and he is fine - then I say goodbye. I think all my clothes are stretched out from him pulling on me. Sara assures me he is done about 2 min after I leave - he is distracted and having a great time with the other kids. He has fun there.
I thought the idea of separation anxiety happened earlier than this, not when they are almost 2. I know it will soon pass, but until then, my heart breaks, and I hate to hear my little angel be so upset.