Hi I've been there and not too long ago either. If your son has been diagnosed with spd i would let some of the sensory therapy work before a behavior specialist, unless they have experience with spd. My son is 41/2 and is hypo sensitive also. He also has social and relationship issues.
we work with a clinical social worker with sensory intergretion training once a wk for an hr. She helps us build our parent/child relationship as well as social skills. Our son between the mild to moderate spectrum, but had gotten to the point with tantrums that i could barely leave the house w/o help. Your child is not the only one w these problems. I've felt the same way so many times. I only even heard on spd in Jan when we took our son for counseling. Thankfully they could see it for what it was. I thought he might be ADD,ADHA, or even autistic. We've had him evaluated by a child psychologist and so far spd seems to be the only thing going on. Since starting counseling and ot (twice a wk for 30min) he has become a different boy We still have our meltdowns and every day is a marathon till bed w sensory play, music therapy, one on one relationship play. But its worth it when he is able to communicate w us and calm himself down b4 completely losing it. Try asking ur ot about music therapy and maybe look for a counselor w SI experience to work on behavior issues. I will keep ur family in my prayers. Just keep at it. If you have any questions u can private message me or post