Brief Answer:
Looks likely to be Herpes2 infection.

Detailed Answer:
Hello
Thanks for your query .
Based on the facts that you have posted it appears that you have acquired Herpes 2 infection or Urethritis after sex .

I shall be happy if you can post me few more details to make comments on your problem.
1) Was it a unprotected sex?
2) Is thee any itching at the site of lesion?
3) is there any discharge from the lesions?

If possible kindly upload photographs of the lesions and urine report

Based on what you have described it looks to be either Herpes2 infection with infection of Urethra (Urethritis).

Please consult qualified Dermatologist or Specialist in sexually transmitted diseases for clinical examination and get following basic tests done to confirm the diagnosis.
1)Swab Test and Culture of a fluid from lesion.

Since there is improvement in your symptoms after taking Doxicycline continue taking it for one more week . You can take Acyclovir twice daily in addition to Doxixycline .

Hope I have answered your query , Please feel free to ask if you have more questions I shall be happy to help you.
Thanking You with Regards.
Dr.Patil.

---

Brief Answer:
Sex with broken condom is unprotected sex.

Detailed Answer:
Hello
Thanks for follow up . Though you have used condom which got broken can not be considered as unprotected sex.,

Please get the tests done which I have suggested in my reply earlier and continue taking medicines .

It is bound to get cured .

Ensure to wash your genitals with warm water twice daily .

Ensure to avoid sexual intercourse till it heals up completely.

Thanks and Regards.
Dr.Patil.

---