Calf injury problem

Hello. In need of help and worry because I’m training for LA marathon and afraid I won’t be able to run it. I have a discomfort very mild pain on the bottom of my right calf area down to a bit of my Achilles. Worried it might get worst .

This issue started 3 weeks ago post half long run , It felt good . I had a rest day after and then an interval session the following day . I crushed that run to but then after that I started having pain in the area I mention. That week was a deload week for me so I actually couldn’t run at all because of the pain. When I run or walk I had that discomfort on the bottom of my calf.

The following week after my deload week, I was feeling better but still unsure and concerned. I ran once more on the Sunday and then I rested more and ran again 4 days after that.

This week I Tuesday and Thursday, just a lot of tightness and the feeling of fatigue on my right leg. My left completely find. Today I tried to run but as soon as I started running, the pain still there. I stopped and just went back . Now just to mention , this issue happens throughout the past 3 week , when I did run, it wouldn’t go away. And to mention it was all easy run post this problem.

I’m missing all my runs and workouts, kind of just bummED out because I was making so much progress and excited for the marathon run. Now I don’t know what to do, it hasn’t healed in 3 we eks , I don’t want to lose my progress. I want to train . I do want to say it has gotten better that I was able to run twice this week with a lot of tightness .

What should I do, the run is in 3 weeks ?