My dogs act restless like this when they have been bit and are having a reaction - they will try to "get away" from the irritant by hiding under chairs, beds, in closets or small spaces.
While the depo might have helped take care of the hives, it might not have gotten rid of the itch/irritation loing term and he might still be reacting. I would suggest giving benadryl (1mg/pound - usual basenji does is about 25mg tablet) evey 8 hours. Giving it should not hurt and might help to calm him down in more ways then one as it has sedative properties to it. I would give for at least 5-7 days.
If you can not find any little critters to account for his problem - I would look at anything he comes into contact with causing it then wash with no dye, no scent, enviro soap/laundry detergent or else get rid of it.