Thumb Injury and Deadlift

Im a beginner, and as of August I have been doing Starting Strength. I hurt my thumb in October, preventing me from lifting until April. Due to school and other contraints (and having lost a lot of motivation as I watched myself get weaker again) I did not restart SS until three weeks ago. Its only been 3 weeks and my bench is up 20- 25 lbs and I can do 5 dips, instead of 0.

My problem is that I still cannot perform a dead lift without causing my thumb to ache uncontrollably for a few days after wards, and I would like to know what other exercises to perform to replace dead lift, or how to heal faster.
I already perform Rows instead of cleans, and do pull ups in addition to SS.