Please help.

My passenger headlight goes off on me after a short period of time I turn the headlights off then back on and it comes on for a little bit then goes off again I changed the switch and drove all over and it diddnt turn off until I pulled in my driveway smallest bump ever! It shut off I parked it and shut the vehicle off i turned the lights on and the passanger headlight shut off i turned them off and back on again and it still did it I have a 2000 gmc jimmy diamond edition with HID's could the headlight be be overheating? could it be the lowbeam relay? its the only light not working properly I priced the headlight and its expensive for the balast and the bulb but it doesnt seem to be the balast or the light if its a ground where do I start troubleshooting with this kind of light? thank you>>I should prolly add that it has done this before then stopped for about 2 months now its doing it again can anyone help with some solutions
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