Brief Answer:
Allergy. probably drug related. to confirm.

Detailed Answer:
Hello sir and welcome to HCM.
I am Dr Dinah and I will be answering your queries today.
Both these drugs that you are taking have been known to cause allergic reactions in some cases, especially the skin patch. But most drug reactions occur immediately after starting the medicines. It is rare that you have developed a reaction to your regular medication after 3 months.
We must also consider any other possible cause. Was there a change in your regular brand or dosage of medicine. Any new drugs that you have taken recently?
Any drugs beyond the expiry date?
Any oils, lotions or applications on the body?
Do try and recall any general causes of allergies that you otherwise have, such as, to dust, pollen, certain foods, any outdoor activity, chances of insect bites,etc.
Any of these could have also caused the allergic reaction.
In any case, it is possible to develop allergy to your medication. Keep a watch on your rashes. Check their progress and note if they are spreading.
Are they present on your palms or soles? Do you have any swelling or blistering on your lips, mouth, genitals, or redness of eyes? Any difficulty breathing ,or swelling up of the face, tongue,neck,etc? These symptoms can indicate a more severe drug allergy.
If you are able to think of any other aggravating causes, do avoid them. If it is being caused by the drugs itself you will need to stop taking them after consulting your treating doctor, and watch for improvement. Once you have an allergy to a substance, it will usually recur again everytime you are exposed to it. So alternatives will have to be considered.
So, before stopping your medicines, consult your regular doctor and discuss these symptoms with them as well. There are certain tests that can be done to check your sensitivity to the drug, and he/she may advise this if required.
In the meantime for the allergy, you can continue the benadryl regularly for 3-5 days. Apply a calamine lotion on the welts 2-3 times a day. If the itching is severe, or new welts and wheals appear, do visit the ER and get a cortisone shot to help.
Do get back to me regarding other possible causes, and any new or progressing symptoms. You may upload an image if you wish.
Feel free to contact me with any doubts or clarifications you may have.
have a nice day and take care.

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