lump on dogs foot

Can anyone help with what this may be? Is round hard and red . 
She gets yeast infections in her toes all the time from allergies so I didn't think much of it, went to put the cream we have from the vet for yeast on it and that's definitely not her normal allergies. 
It's very solid and hard, doesn't seem to bother her though. 
Will be taking her in on Monday, just seeing if anyone knows what it could be?