Its been a while since I've been told the game is too hard. Normally I try to err on the easy side.
I've been thinking about implementing a couple of simple minigames to break the combat and award the player a little of extra money before a round, but for the time being consider buying some worts and aloes. The shop is readily available during the first few levels and they are only $1 each while a regular fight usually nets you $3 so they are both affordable and heal a lot for that stage of the game.