Need advice on disability or maternity leave!

I’m 27 weeks pregnant for that last month and a half I’ve had bad muscle and nerve spasms on my upper back and on my rib cage in the front right side . I went to neurologist he said I’m having spasms and ordered I do physical therapy for 3 months 3x a week. I’m in severe pain I can barely stand or sit. Only relief I get is when I’m laying down and still in pain. The lidocaine cream and patches he prescribed me aren’t doing anything. How am I still suppose to work a full time retail job if I’m not getting put on any physical restrictions and the more I move around as the day goes by, by the time my shift is over I’m crying in pain can’t even drive home. I’m suffering I feel baby is suffering with me. I’m scared I will go into preterm labor due to pain and stress because of it.