choking, arching, crying, coughing...help!

beck8008

lo was fine with feedings all morning, but suddenly this afternoon we are having a hard time- he's choking, arching away but then attacking my boob like he's starving, then he starts coughing while feeding and pulls off crying- i'm not sure if i actually have a forceful let down so just in case, i tried reclining while feeding, pumping for a few minutes to get rid of some of the flow and i've also tried a bottle today- nothing seems to help- lo is miserable anyother ideas of what this is? tia