I only had girls so I can't speak from experience on the car of a little boy.  My first question would be if it is accompanied by a fever?  He's only 6 months so infections are really important to treat right away. 

When they're so little they don't have a lot of reserves to hold them through battling a long drawn out infection, ya know?  So see a doctor in the morning, or if he has a fever, I'd go to the doc right away.  Also, doctors will want to know right away if he has been "acting" sick.  Since they can't tell us what's wrong, the doctors rely on mommy's instinct, and his behavior.  hashe been nursing as usual?  Needing more comfort?  Crying with wet diapers?  More uncomfortable than usual?  Sleeping more or less?  Just go with your gut - it is usually right.  And if you are a worry-ing type of mom - just get it checked out - it will make you both feel better!  :)

Don't put medications on an infant that small either.  I would put him in a nice warm bath with epsom salts or regular table salt - it will be soothing and disinfect, and speed healing all at once.  I'd also leave himwithout his diaper as much as possible... on a towel or in the tub, etc.  Air is good to aid healing too... 

Hugs to you both,

Cathy

It sounds like it could be a bit of diaper rash, maybe?  Try letting him "air" out as much a possible.  Also, before you put the dipe back on, try a little vaseline on the area...

I would call the doc if it doesn't go away.