This could be a variety of things, sadly. From personal experience, "jerking" could be caused by:
- Worn engine mounts.
- Harsh clutch engagement.
- Weak battery.
- Fouled/worn spark plug(s).
- Low compression.
- O2 sensor problems.
- Bad coil plug(s).
That's not a definitive list, but I'd check the easy stuff first. Is your check engine light on? If so, solve that first. If not, make sure your vehicle is tuned up and is up to date on maintenance.