Church Nursery and Separation Anxiety

My son is having a rough time with church nursery the past 2 weeks because they moved him to the 1-2 yr old class. I had to go sit with him for an hour because he still hadn't calmed down after 15 minutes after I dropped him off. I think he got very used to the teachers and babies in the other class but it seems crazy when the other little kids are just sitting there playing with toys and he's screaming like they are all monsters. He calmed down when I was with him but I don't know how many weeks it's going to take him to adjust and there's not much point in me going if I can't even listen to the sermon. Last week they just put him back in the younger class and he calmed down but they don't want him walking all over the little babies and the oldest ones in that class just started crawling. He's been going since 5 months and the first month he wouldn't take a bottle from the nursery workers but since then we had very few problems, he even naps well. If he were in daycare I know he would probably adjust quicker, but right now I always thought it was good to have him there to see other babies regularly and the ratio is great at 2:5. Has anyone had this problem before? I could keep him home since my MIL doesn't go to church and watched him when he was very young but I don't feel it would help in the long term. Every other week I teach during the second service and we are there from 9:30-12:30. My wonder weeks book says there is a leap at about 55 weeks so I'm hoping it is that and will resolve in a couple more weeks but I hate hearing my baby sob in a scary way. Here he is later in the afternoon yesterday when he was perfectly happy with his grandpa (my dad) at the park.