baths are fine hun as long as they're not too hot. I had baths nearly every day of my pg because of muscular pain. They will be fine right through the pg until your waters break.

Panadol is also fine for temporary pain relief.

Here is a recipe (lol) for a home meade heat pack.

Fill a cotton tube sock 3/4 of the length with plain white rice and sew the end shut. Heat this in the microwave on a pie plate (to keep it clean) for 2 minutes. I usually put a washcloth under the heated sock at the beginning because it is really warm. As it cools, I remove the washcloth. It will stay warm for about 20 minutes. Mine have been used repeatedly
Tie it with a hair elastic if you don't sew - or even tie a know in the sock.

Hope you feel better soon xx