Can I safely use a heat bag for cramps and contractions?

I’m a FTM, and currently 38 weeks pregnant. I just saw my OB yesterday. She checked my cervix and I’m 3cm dilated. She then did a stretch and sweep. She did the same thing a week ago and it caused cramping for about 48 hours afterwards. The same thing is happening now, but much more intense. I think these may actually be Braxton Hicks contractions, as they come in waves, but there is no real pattern to them. Very uncomfortable. I’m scheduled to be induced tomorrow evening. In the meantime, I’m wondering if it is safe to use a heat bag? I have one of those fabric bags that are filled with beans/rice that you can microwave to warm up. I used to use it when I had bad period cramps so I’m thinking it may feel nice now too, but would the heat be bad for the baby?