Sounds like tennis elbow. A bad, bad case. If it is, my guesstimate is minimum 3 months of no tennis, no weights, and restricted activities. Take it from someone who has had this 3 times. The first time I got dared to play someone while I had the tendinitis, and it took me out for a year.
Lesson: don't muck around with this. This is a very serious injury. If it's hurting that badly, chances are good that the tendon is torn, and you are going to have to give it time to heal.
Why doesn't it hurt while you play? That's what I asked when mine was ongoing. It's because the damage is done, and because the arm basically goes numb while you play. You're focusing on the match, instead of the injury. Some injuries can not be overlooked during a match (groin, shoulder, knee, etc.), but most anybody can play through elbow. Take my advice: let it heal.
Head Microgel Prestige Pro, 4 3/8 (L3), Lux ALU Pwr 16 mains@58 lbs/PSG Orig 16 crosses@61, rubberbanded, & Wilson Pro white overgrip.