Post pregnancy skin problems. Medicine!

My kid is now 1 year old. After pregnancy I observed very significant changes in my skin. 1. Extreme dandruff with Dry hair. Hair suddenly became grey in large patches along with extreme hairfall. 2. Sudden and extreme Blackening of skin (pigmentation) on neck, armpits, privates, which was a very sudden and happened inspite of daily cleaning routine. 3. Consistent armpit pimples 4. Face skin is also damaged pigmentation and pimples. I never had any facial skin problems ever. Not a single pimple before pregnancy 5. Also I never had skin tags before pregnancy now I've suddenly developed lot of skin tags all over body. 6. Overall skin texture, colour and health has seriously deteriorated. Also I've gained 25 kgs in pregnancy out of which I've lost 8kgs. Pls suggest Medicine