hot tubs?

i have a hot tub and i've not used it in a while the temp is set at 40 degrees but i changed it too 32 let it cool down over the last couple of days i'm 33 weeks pregnant and thought this would help with the pains i have been getting in my pelvis and back i was in it for about 10 minuetes but since coming out i've been getting pains down below and cramps, i googled hot tub use and it says its not allowed 😑 anyone have any advice😥