Hey everyone! I am completely new to cycling and looking for some trainer advice.

A little background:
I've had 5 back surgeries. I've been riding my mountain bike here and there over the last year averaging 12-16 miles without any problems with the thought that I would upgrade to a road bike for longer more intense rides, if my back could handle it.

Fast Forward to now:
I bought a Kickr Snap 2 weeks ago, bought a new saddle and had the bike shop adjust it to the proper height. Went home and over the next week managed to ride 4-5 times for 30 minutes each at my normal speed. After this week I have found that I have tremendous back pain and sciatica that weren't a problem before. I had to take back the Kickr because of the return policy while I could figure out 1, if I can recover and 2, if there is a different trainer option.

My question is, do you think it's the trainer? If I can ride on my mountain bike with my seat the way it was and be fine outside, is it possible the rigidness of the stiff trainer was the cause? I've seen trainers like the Rock and Roll out there and wonder if that motion is better at transmitting the forces into the bike instead of up into my back. I'm curious if anyone has had an experience like this because I can't seem to find anything out there.

I really want to get into long distance road cycling but need to figure out if my back can handle it before I invest in a $3k cycle.

Any help would be greatly appreciated!!!

For the record, I LOVED my 5 sessions on the trainer despite the pain. I couldn't wait to get home and get on each night