Hi. Thanks for your query and an elucidate history. Read and understood your problem of very lax left side of the scrotal sac and getting hitting when you are travelling on motorcycle causing pain in the lower abdomen. This definitely is a symptoms that needs investigations and treatment. You are working in the hot climate causes enhancement of the problems as there is extra slackening of the sac making the testicle to appear as a clapper in bell appearance. The commonest reason for left testicle to hang so much is low is the large varicocele. This increases the internal temperature so much that the scrotum on that side has to constant relax to dissipate the temperature. I would advise you the following in such a condition: Get a clinical evaluation from Urologist or General Surgeon. Ultrasonography and color doppler Preliminary semen analysis is a must as as well the tests of blood, urine. Get operated in the classical way to get the results, , once the testis is pulled up the scrotal skin gets adjusted to the normal position.