When I had returned (μο υποστρεψαντ),

while I prayed (προσευχομενου μου),

I fell (γενεσθα με). Note dative μο with εγενετο as in verse Acts 22:6, genitive μου (genitive absolute with προσευχομενου), accusative of general reference με with γενεσθα, and with no effort at uniformity, precisely as in Acts 15:22; Acts 15:23 which see. The participle is especially liable to such examples of anacolutha (Robertson, Grammar, p. 439).