you must be new manager - the game is teaching you early how to spend your tokens on healing packs - it's a good training so you get used to it and by the time you reach level 6-7-8 you won't have problems buying healing packs regularly.
Also because you have not developed your stadium a lot the injuries are longer, take longer time to heal, but the good news is - no matter how bad your player is injured is only costing you 15 healing packs to heal any injury longer than 5 days... Since I played this game for a while - I think that's cheap.... you'll get use to it in a few months...