I used to get them a lot. When my allergy to polyester was mild. For I have fine hair on arms and legs. So the skin gets a bit tough and the hairs can't make it through. So if you have fine hair and thick or firm skin, then this can happen. For a person with allergy to polyester, the areas of contact which are most sensitive will do this. Back of upper arms, from the polyester they put in threads of cotton clothes for strength. so the sleeve thread around the end of it rubs more there also.
The inner thighs for the thread in the pant seams. Is a sensitive area. Sometimes the butt cheeks from sitting on the pocket thread will become rough. Like tiny goose bumps also. The top of feet for the shoes are tight to the skin and probably have polyester in them. Or from the thread around the lace area. If shoes are polyester based, then the bottom of feet are tough and don't react. There will be a very slight bump to the raised hair just from the hair being under it. For you pleasehelp, roll your short sleeves up twice and this will kep the thread away from your skin and you can find out if this is the problem for you. Wear loose fitting all cotton clothes. Both of you. And see if this gets better. All cotton socks can only be found at JC penny. That I know of. Made by niki or however its spelled. And they are ankle high. Polyester in all other socks I know of. And polyester in socks could make your body do this any place . Not just legs. So try the socks if you are concerned. For there will likely be no other suggestions to stop this from happening. So you might as well try this. I am allergic to polyester badly. So these things I know. Have had both yours symptoms. Wearing 2 pair of socks if you can fit them without your shoes being too tight. Keep laces looser is all. And first pair goes on inside out. To keep the poly in threads of them away from skin. Wear loose fitting 100% cotton clothes so the threads don't press onto skin. Even though you may not react a lot, the allergy bothers the nervous system. Can make you uptight easy, or anxous. Unable to sleep easy, from polyester in mattress or sheet. All cotton sheets with a dense cotton blanket under sheet. Pillow is filled with 100% poly. So you may have dry scalp from that. 100% goes right through pillow case is why. I am not saying for sure you have this. But many do and don't know it. And it sounds just like it to me. Give these things a try to find out. And be glad they are mild reactions!
I would love if someone could help answer this question. I have been having this problem for years. I also get these ingrown hairs on the back of my arms. I exfoliate and moisturize as much as I can but nothing seems to work! Someone, please help us!