As you know there are different types of allergy symptoms. Once of the symptoms would be a rash. This is when you might want to get a dermatologist's opinion. Dermatology is the study of the human skin and blemishes. Rashes are part of the dermatology world. If you get a rash from an allergy, then it should go away by itself over a couple days or so.
Sometimes, because you scratch, you will get an inflamed rash that needs medical care. This is when you might want to make an appointment with the doctor. Your doctor will give you a cream or anti-bacterial pill so the infection can be cleared up. You may want to ask your family doctor for a referral. Most dermatologists want a referral, because they are a specialist.
Once you see the doctor, you need to tell and show him or her where your rash is and explain what kind of allergy you had to cause such a reaction. He may even suggest to you a diet plan to flow so that you can avoid going through so much again.
Once you get your prescription, you should follow the doctor's orders to the "t". If you do not follow his orders, then it is most likely that the bacterial infection will spread and that will be even more embarrassing.
You should never scratch a rash of any kind. Scratching rashes spread them and if will cause an infection because of the dirt and germs that are found underneath your fingernails. Since the germs on your hands are usually what cause the bacterial inflammation, you should watch your hands regularly and always before and after applying any creams. Taking good care of yourself is most likely part of the order's your doctor will give you.
Allergies that cause a rash are usually from touching or eating something that you shouldn't have. You should check with your doctor to see what exactly made you break out. It might be your fabric softener or the type of clothing you were wearing. It is best to avoid using that brand again or the type of fabric.