PHILADELPHIA — After a goal late in the third period from winger Gerry Mayhew put the Flyers up 3-2, it seemed like the team was on its way to victory for the second time this month. Then, as it often has for the Flyers this season, the bottom fell out in a 5-3 loss to the Washington Capitals at the Wells Fargo Center on Thursday. Less than 15 seconds after Mayhew’s goal, Garnet Hathaway deflected a shot past goalie Martin Jones to tie the game with less than three minutes to go in the third period. Then, Hathaway scored the game-winning goal roughly two minutes later to put the Capitals up, 4…