i know you lost a lot of weight, and that is awesome.!!
now that you lost the weight, your metabolism is catching back up to you. the gain could be from running, it does build muscle. if it is from just gaining weight, vary your cardio routine. looking at a scale doesnt gauge how you look.
that is a pretty lift. i dont know how you lift, but next time, try this to get 300x1.
warm up 135x12
225x4
265x1
300x1
a lot of people tire themselves before they max out.