My Daughters Son Who Is 4 Month Old Weighs 17

my daughters son who is 4 month old weighs 17 pounds has Head colic about 1 month old they give him acidophilus a prescription antacid medicine and colic drops only at night and a sensitivity formula the last week it has gotten way worse the only thing she can do is sit in the bathroom with the water running to soothe him he just cries and cries and he does not naps other than 10 minutes here and 10 minutes there and it's been that way since he was born but he pretty much does sleep through the night would it be safe if she gave him some Benadryl at the recommended dose for his weight she had colic as a child and so did baby's daddy that's what I gave her but she's worried about giving it to him it. Also somebody said to try goat's milk or an organic soy milk but my main concern is if it is safe to give him Benadryl so that he doesn't cry and cry and cry the poor boy is definitely in pain he always wants to be in the upright position and probably is teething a little