Loose skin after losing water weight

Hey, i read somewhere that if you have foodintolerance and eat the things you do not tolerate you can get water retention, and logicaly if you stop eating them you will lose this water weight, so i did a foodintolerance test and stopped eating the things i was intolerant to and so i lost alot of water weight really fast, in like two weeks i lost 20 pounds...

What conserns me is my face..i've ended up with alot of loose skin that i cant get rid of..i know you shouldnt lose weight fast couse you might get loose skin, but the water comes of so much quicker than fat..and now i dont know what to do..but i'm only 20 years old..should'nt it be easier for me to tighten the skin up with time than if i was like 40?.. I've read somewhere that you can try Face Exercises, and you should drink lots of water, skinbrushing and exfoliate often and so on..and im doing this but i guess what i'm wondering is - Will the skin tighten up with time or will it not?