Pain in my butt and lower back when bending?

Muscle strain. Most likely you've strained your back & gluteal (butt) muscles lifting something improperly. That's why it's so important to bend at the knees when picking something up rather than just bending straight over from waist (most people aren't warmed up or limber enough for this - watch pro golfers grab golf ball after sinking putt). Go see doc if any pain down legs, loss of strength or incontinence.