Does my baby have an allergy or a stomach bug?

My 6 month son's stools have increased in frequency for the past 11 days now. He is a breast fed baby who won't take a bottle. When he was a younger he spit up a lot (projectile at times) and I thought it may be a milk allergy so I cut out dairy and it seemed to improve a little. I still don't drink/eat cows milk, yogurt or cheese. I try to eliminate most foods containing milk, but it's very difficult to cut out everything. Nothing major in my diet has changed over the past few weeks other than I may eat more peanut butter than usual. When the stools first started to increase I noticed a fowl smell and they were extra watery and then no smell after a few days. The color changed from normal mustard to bright green to now a dark green. The stools are still runny but not so much watery anymore. They have always had mucus in them for the most part it seems. Today he had a dark green springlike mucus look with no water. My concern is how often he is still going. He went from never pooping in the middle of the night to pooping 3-5 times at night. On average the past 11 days he has had anywhere from 10-15 stools in a 24 hour period. Some are a lot and some just a little. But he definitely stools right after he eats and sometimes 2 more times before the next feeding. I'm still feeding him every 3 hours on average during the day and he eats twice at night (usually 1ish and 5-6ish). Do you think the stools could be from over feeding or too much fore milk? Please help.