A couple questions

Question
Hi,i have a couple questions about my guinea pig,Henry.
I got him about 2 or 3 weeks ago and he's still very timid.
Although he won't bite me i try to pick him up.
He is sort of like my fish.If i go up to him he runs and hides.
He also has a bald spot on his head,should i be concerned?
Also a few days ago his hind area was discolored it was darker the his regular coat.it looked oily but i couldn't touch it.(because he ran away from me).
I think he has been scared of anyone because when the guy at  petsmart was getting him out of the cage he chased him with his hand and picked him up by his hind.I think he was traumatized on that day and is scared of anyone who comes near.
Please help me and Henry so i can give him the much needed love.

Answer
Hello,
To help your guinea get used to you every time you go up to his cage give him a tiny little bit of grass/treat when he comes to you. Soon he will run up to the bars every time he hears you coming. For picking up firstly make sure you do it as quickly as possible because otherwise he will get more and more terrified. After you have caught him give him some food that he enjoys while on your lap so every time he comes out he will think yay more food. If the bald spot on his head is in a crest then that is normal. On his hind area the darker oily part is called the grease gland and it is normal on the guinea. You will need to clean it quite often though, try baby johnson's shampoo to get it out. The grease gland in a guinea pig is located just above where a tail would be (if guineas had a tail). Some sows and some boars have active grease glands that can be a challenge to clean. Pet owners claim success with these methods of spot cleaning the area:

Malaseb is a very popular cleaner. Shampoo the problem area with this product, let sit for ten minutes and rinse. But I would still recommend Johnson's.
It could be possible he was scared by the chasing around but maybe he just needs time to settle in and sometimes it is just in the guineas personality.
I hope this helps and please don't hesitate to ask again.
Alex