Spikes happen for various reasons and they usually last for a day or two as you've mentioned. Many people that have tinnitus due to "noise exposure" will experience spikes. The cause often relates to an underlying condition associated with tinnitus caused by noise trauma, which is Hyperacusis. This takes time to improve, either naturally or with treatment. If it does not make improvement naturally and there are various things a person can do for self help that I've mentioned in my post: Hyperacusis, As I see it. The link is below. Professional help will need to be sought. If hyperacusis isn't treated or improves by natural means spikes will always remain a problem. In the majority of cases most people see significant improvement with time. I once had very severe hyperacusis that has been cured for 20 years.
Michael
PS: Spikes that last for 1-2 weeks could be an indication of overusing hearing protection or keeping away from natural everyday sounds. Both of these things can lower the loudness threshold of the auditory system and make it more sensitive to sound. Stress and anxiety can also prolong the duration of spikes and counselling with a Hearing Therapist may be needed.
https://www.tinnitustalk.com/threads/are-spikes-from-loud-noise-permanent.18156/
https://www.tinnitustalk.com/threads/hyperacusis-as-i-see-it.19174/