I've been having forearm fatigue in my right arm for 6 weeks now. it started when i was using my computer. there is no pain. what could this be?

Strain: This is most likely muscle strain from overuse or simply from positional issues when using the computer and resting the forearm followed by altering your technique or even trying a wrist, forearm brace when using the computer may help. A consultation with an occupational therapist may be worthwhile if you get no relief from these measures.