Remember, you canât out-exercise a bad diet so if youâre eating too many calories each day, it doesnât matter how much walking youâre doing since you will not be able to burn it all off. So, focus more of your attention on the foods youâre eating.
1 Keratosis pilaris causes numerous small, rough, tan or red little bumps around hair follicles on the upper arms, thighs, buttocks, and cheeks.  Keratosis pilaris creates the appearance of gooseflesh, goose bumps, or chicken skin.
You may develop a rash under your arm when wearing a shirt that was washed with a particular detergent or treated with a chemical. Metal, such as jewelry, can also cause underarm rash. Other forms of contact dermatitis include exposure to certain plants, such as poison oak or ivy, an animal bite, or an insect sting.Lyme disease is caused by tick bite, which can first display as a circle with a bullâs-eye pattern, then progress to a rash.ashes can vary in location, pattern and extent and may occur in any area of the body. A rash under your arm can have a variety of causes, and it may indicate something occurring around the underarm itself or suggest a systemic (body-wide) condition.