<s>[INST] i have a rash on both my knees and elbow. it's very itchy, red, and hurts a bit. i am concerned that this may be more than an allergic reaction, because i cannot think of anything that i have changed concerning products, etc. in a very long time. how do you differentiate between MRSA and a regular skin reaction to an allergen? [/INST] Hello,I read carefully your query and understand your concern.The symptoms  seem to be related to eczema which often appears on elbow and knees. I suggest using a steroid cream for local application such as Hydrocortisone cream.I also suggest using antihistamines to relieve the itching. The MRSA infections leak pus and this is the major difference between them and an allergic reaction. Hope my answer was helpful.If you have further queries feel free to contact me again.Kind regards! Dr.Dorina Gurabardhi General &Family Physician </s>