thanks alot for the information..
Hello and welcome!
The purple spots can be purpura and petechiae. But since the rashes are non progressive since past 2-3 years it seems unlikely that it is petechiae or purpura.I cannot confirm anything without external examination. Based on the information shared by you these rashes could be due to allergy, inflammation or any bacterial/fungal infection. Other possibilities are eczema, psoriasis or Keratosis Pilaris.It is best to get them examined by a dermatologist. Treatment will depend on the exact cause. I sincerely hope it helps.
Take care and regards!