Sometimes, teams do go through bad periods. It seems that nothing much can be done about it so far. But, try doing the following.
Avoid too much training. Check the average physical and mental attributes rating for your injured player. If the average rating is much lower than the other two (defense and attack), then, maybe you need to add some skill points to that section so that it is balanced.
Check construction section; upgrade the quality of the pitch, add medical facilities and so on.