I started getting stress incontinence a couple of days ago. Will I be back to normal by next week?

Not likely. Unless there is a temporary source - uti, unusual strain, heavy cough due to cold. You can try kegels to alleviate it for a while.
Why incontinent. Most of the time stress urinary incontinence (sui) is due to vaginal prolapse and hypermobility of the urethra. If that is the case, your symptoms will likely gradually get worse over time. Kegel exercises will help most women with sui - if they do enough of them. Sometimes the sui is related to a urinary tract infection - if that is your case, symptoms resolve with treatment of the infection.