Alright keep the temps at 100-110, 110-120 is way too hot.
Get him out of the 10 gallon, it is way to small for even the smallest beardie and he is probably stressed and with such high temps unable to get to the cooler temps he needs to get to.
What type of uvb do you use? Im not going to say for sure but 99% of the time this is the reason for problems.
What do you dust the crickets with? ( This is the other important part)
Cut the waxworms and lettuce out of his died, offer silkworms,collard greens, and squash instead.
What substrate do you have him on? If its sand switch him to paper towels.
What size crickets are you giving him? For his size id say he needs 1/4-3/8 in size.
After these questions are answered and fixed hopefully we can find out why the little guy is not growing
Oh, and about lineage. blood and sandfire are "lines" so to speak but really do not matter, from what all ive seen over the years is people naming off what they are off of what colors they have on them. Im betting the parents did have sandfire and blood in them, but were still brownish.