Boxing tips? I keep flinching too much?

I have trouble flinching whenever someone throws a jab or straight at me. I am pretty decent at the speedbag and i dont flinch when i do the speedbag but i thought the speedbag was suppsoed to help you not flinch? Today i was sparring with a guy at my boxing gym no contact to the face but we were allowed to hit body shots. I was doing good for the first minute i was bending my knees and dodging his shots and getting some body shots but i slowly was losing my stamina then he threw some jabs at me and then all of a sudden he uppercut my solar plexus (middle of stomach) it really hurt like a ***** but i endured it and went on. moments later he hooked my hip and i couldn't take it anymore so i forfeit and it was really hard to breathe and i was a little naesous. the 2nd round he was hitting all my body parts and i blocked it with my elbow and i kept on doing jab then straight to the body so i guess he found out my pattern then whenever i punched he blocked and immediately hit my body and kept doing that then he kept hooking my hips and the pain was excrucciating and idk what to do i was doing good in the first moments of the round but i somehow screwed up and i think it's because of my stamina but also because i flinch sometimes because when i flinch i lose my form then he takes advantage of me and just starts throwing really hard body shots i think he's been at the gym for a while but i only started boxing 1 month ago any help amateur and professional boxers?