Sagging skin or dangling fat that is formed under the arms is not pleasant. The underarm skin is developed due to various reasons. Some of the major reasons include age, diet, lack of exercise and gravity. If you are not careful while working out your arm muscles and taking proper diet, water you may notice a flab of skin hanging under your arms. There are several measures you can take to reduce the loose skin that formed under your arms. Besides your aerobic exercises, you need to do certain exercises that target your arm muscles and triceps. This will help you tone the arm muscles and get rid of those bat wings.
Standing Triceps Kickback

Triceps Stretch
Triceps stretch is a simple variation of the above exercise i.e., standing triceps kickback. It is more effective than the above exercise. It helps you in strengthening, toning your upper arms. It also tightens the backs of the upper arms. This exercise should be practiced by standing with the feet hip-width away from each other. Now take a light-weighted dumbbell in your right hand and extend the right arm straighten it in front of you. Now slowly bring the dumbbell towards your right shoulder by bending your elbow. Take the right arm past your head and hold it in this position for about 20 seconds. Repeat this triceps stretch on the opposite side as well. Perform this exercise for several minutes for both the arms.
Triceps Extension

Single-Arm Medicine Ball Push-Up

I agree with Danny Robbins inversion tables are amazing for sciatica etc, all my back pain is gone in the space of 3 weeks
Where, specifically, is the side pain? Inversion may not work.