Flight speed going down to 25% I need help DX

[Stonemaster5]

I don't know what happened to trigger it, but I was playing the B-team as a bat and my flight speed (displayed on the top-left of my screen) went down to 25% when it was previously at 100% for no reason. I flew very slow and it got annoying. I didn't know what to do so I just re-downloaded the modpack. It worked at first, but about 3 minutes in it started going down again and it was back to 25%. If anyone knows how to fix this, please help.