my leopard gecko isnt eating and im worried he might have mbd

he hasnt eaten in a week, my geckos tank is 2x1x1 foot with correct heating, substraight and hides so i dont think thats the problem. ive had my uvb strip (arcadia T5 pro) for about a year so i think it needs changing but aside from that hes never had calcuim with D3 only normal bc i wasnt aware he needed it. could that alone give him mbd? and should i leave a small bowl of d3 aswell as normal or just the normal calcuim?

hes eaten 1 cricket with d3 calcium which is giving me some hope but im really worried. i saw his hand trembelling which made me thing mbd but i was also making noise in his tank so he could have just been stressed.

is it just a hunger strike and im over reacting or is it serious? any advise? all sorces say different so i dont know what to do. i cant loose him.