What would cause weakness in my antecubital? hurts when i lift things. when i push on it i feel ache/pain in one spot. also a slight pain when i extend my arm all the way with palm facing up.

Overuse tendonitis: must be examined and treated with anti-inflammatory medications.

Biceps tendon: this sounds like a biceps tendon injury or biceps tendinitis. Anti-inflammatories can help. Ice massage and or moist heat to the area can also help. Avoid forceful flexion of the elbow or full extension of the elbow. Avoid carrying anything heavy or pulling forcefully with the affected arm. Can take 6 to 12 weeks sometimes to resolve. If no improvement in two weeks, see your doctor for evaluation.