What you experiencing is very common. Somebody was just posting about it in here last week. They also had it go up then down.

Here is a table of what happens if you don’t treat at .2. As you can see if you wait until .5 you’re going to have to go on ADT As well as salvage radiation if it will work at all.

From Ascopubs about what PSA to do salvage radiation.
≤0.2 ng/mL:
Starting at this level maximizes disease control and long-term survival. Patients treated at PSA < 0.2 ng/mL achieve higher rates of undetectable post-SRT PSA (56-70%) and improved 5-year progression-free survival (62.7-75%).
Delaying SRT beyond PSA ≥0.25 ng/mL increases mortality risk by ~50%.
0.2–0.5 ng/mL:
Still effective, particularly for patients with low-risk features (e.g., Gleason ≤7, slow PSA doubling time). The Journal of Clinical Oncology recommends SRT before PSA exceeds 0.25 ng/mL to preserve curative potential.
0.5–1.0 ng/mL:
Salvage radiation remains beneficial but may require combining with androgen deprivation therapy (ADT) for higher-risk cases.