Freezer Freezing & Leeking

Please help! My Freezer is freezing and leaking. The water is coming out of the back panel. I removed the panel and the evap/heat assy was partly frozen. I checked the drain and there is nothing clogging it. Although if there is a clog I can’t see what’s clogging it and it does seem to have water building up or coming up from the drain. Does anyone have an idea of what might be wrong and how much the repair might cost me or if I should just start looking for a new fridge?