Suggest Treatment For Blotchy Skin And White Bumps Around Elbows

female, 18, 5 8, 146. Asthma, history of hashimotos disease in family. about two years ago at the beginning of summer I was tanning and large portions of my back and stomach simply wouldnt tan(most of it except the sides/around the edges), it looked very blotchy around the edges. it didnt change color, just didnt tan meanwhile some parts did, making it look really splotchy. i forget, but maybe a year ago i started getting whitish bumps around my elbows(size of a peppercorn) as well as lighter colored splotches(never bigger than a nickel) any idea what these skin issues are and if there is a quick fix? would vitamin d help? the bumps have reduced recently but they re still visible, just not as white or flakey. some seem more like scars at this point, but some still feel raised.