dear user first i feel your worry about that problem and i know you are confused now and want to find asolution but there are items you should know.........allergy to antibiotics doesnot be diagnosed and confirmed from your history of taking it and rash appearance as there is always misdiagnosis of allergy to antibiotics...if you had taken antibiotic in the past and develop rash it doednot mean you are allergy it may be because of infection or other causes..............so you should be confirmed to have allergy or not thraugh tests........skin test is very helpful for that we inject intradermal dose of antibiotic detected and we repeat the test for that ...........you didnot mention in your words that you had skin test for these drugs ........if you think that you had symptoms or confirmed diagnosis of allergy in the past it doesnot mean you are allergic now............allergic reaction to drugs differ from time to time because of certain immunolgical reactions of the body..........you asked about natural remedy but it is not treatment it is just helpful as drinking alot of fluids and hygiene practices ..... multivitamins especially vitamin c and antioxidants have agood effect in improving immune system to fight infections.........but please you should do repeated skin test for every antibiotic detected and you will have avery helpful results that get your worry out....wish you healthy life