Hi Raven99 and Welcome to Healing Well Chronic Pain Forum! Sciatica can be extremely painful, I have problems with it myself. Mine also comes and goes but I also take pain meds to control it. Sounds like you need an MRI to find out what is going on, as was previously mentioned, the weakness in your legs is of concern, can you move your legs and feet normally, no foot drop or anything? If you leg gives out on you or you find walking difficult, I would recommend going to the ER right away. Also as was mentioned any loss of bladder function, or any thing like that, also go to the ER. Sciatica is often caused by nerve root impingement in the lumbar area of the spine, it can be painful and in some cases it can cause major problems, so it is not something to just pass off lightly!
The 24th is a long way to wait, so please take it easy and try not to do anything that will cause you more pain, i.e. lifting anything heavy or bending over. Hopefully your doctor will run the test needed to find out what is going on, and can give you some relief!
Good Luck to you! and again Welcome to the Forum
White Beard