Ok I was changing Maddie's diaper tonight and for some odd reason I decided to look at her stuff down there and it looks like its a lil swollen like maybe she is possibly going into heat

Oh dear God I hope not!!! Bailey hasn't been acting any differently around her and he hasn't been trying to hump her........I took a picture of it.....
Maddie is expected to go into heat towards the end of this month or sometime next...
I don't want an unwanted pregnancy so I'm kind glad if this is a sign I am catching it before Bailey turns into a MAD man....
What do you guys think it is???? Is she about to go into heat???? PLEASE HELP ME!!