My iPhone 6 bluetooth is glitching when connected to bluetooth speakers, the music doesn't play smoothly

Today I purchased a Gear4 Espresso Bluetooth speaker after seeing first hand how good they were as my friend owns one. Once I took the speaker out and paired it with my phone the music played clearly and smoothly the whole way through however, a few hours after this I tried playing my music again and although my iPhone does find the speaker and connect successfully- the music does not play properly. Songs are lagging and start and stop constantly throughout the song, I don't know if this is a problem with the strength of my iPhone's Bluetooth? How could I fix this problem? Thank you!!!