I had what I believe was a similar forearm pain to yours. I got rid of it by always doing wrist prehab--closed and open-chain mobility and a little stretching--before my gymnastics (this is a big part of the routine
). Since that time, I also stopped doing my planches on parallettes (that was the worst for me) and now do them on the floor (fingers forward).
I also did some laser therapy (3-4 sessions) and changed how I hold my daughter on my arm--instead of holding her with my forearm fully supinated, I rotate my forearm to a more "neutral" position. I definitely made sure I avoided all nightshades during this period. Holiday cheat eating and stress also likely played a role in increasing my general inflammation levels.
After a week of "treatment", my pain went away.