Re-introducing piggies

Question
I have 2 male guinea pigs about 4 months old.  They've been together happily
for about a month but then one got a fungus and they had to be separated
for 2 weeks.  I have re-introduced them today but they aren't friends like
before.  They chase each other, mount each other, and stuff like that.  So far
no one has bitten badly enough to draw blood.  

Do you have any suggestions for me so that they'll be friends again?

thanks for your help.

Lily

Answer
Lily,

So sorry for just now getting back to you, been working overtime this last week at work.

They are both reaching that age where they need to decide who is going to lead their group. They are group animals and so there is always a leader.

Keep introducing them in a neutral place and allow them to work everything out. Let them go through the motions of the dominance behavior. They'll have it figured out soon enough and then will be friends again. Just give them time to figure it all out.

I hope this helps,
 Take care,
    Jules