Good evening
The rash appears to me as an allergic reaction to some of the ingredients in the collagen powder that you are having.
Next Steps
Apply Calamine lotion topically over the rash.
Tab Levocetrizine 5mg 1tab at bedtime for 03days
Health Tips
It is advisable to avoid the consumption of collagen powder in the near future.
Also I would like to know if you are allergic to any food items,the new additions in your dietary pattern and any other symptoms apart from the rashes that you are experiencing.
Regards