Probably the monitor is on its way out. To check, plug in another monitor from a friend or neighbor and see if the wobble is still there. If not, you will need to replace the monitor.
If the wobble is still there, then the video chip is going out. If you have onboard video integrated on the motherboard you will have to add a video card if a slot is available on the motherboard. (You don't list your specs so we don't know if a slot is on the board or not.)
If you have a video card already, you would need to replace it.
J.
Cooler Master Elite 430
Asus P8Z68-V PRO/GEN3
Intel Core i5 2500K, 3.30 GHz
ADATA 8 GB DDR3
EVGA GTX 560 1GB PCIe
Sound Blaster Recon3D PCIe
1 TB Seagate Barracuda 7200 RPM
P/S: Corsair GS800
Windows 10 Pro 64 Bit
. . . by Digital Storm