Thanks for writing.
Without seeing the red bumps in-person, it’s very difficult to give an exact answer but I will give you some general information.
There are lots of different things that can appear on the skin, and they are not always related to sexually transmitted infections. For example, you mentioned heat rash. However, we don’t usually see heat rash on the penis shaft. Also, fungal infections are very common, especially in hot weather, but we don’t usually see fungal infections on the arms. It could be a combination of heat rash/ fungal infection.
There are some red bumps/rashes that can be caused by sexually transmitted infections, but few that are so widespread over the body. It doesn’t sounds like Herpes to me, as Herpes usually appears as 1-10 bumps in an isolated area (not on thighs, arms, stomach etc.). With bedbugs we don’t usually see bites on the penis, but it is possible. Scabies can affect the genitals as well as other parts of the body, and that is possible as well. Scabies is typically very itchy, especially at night, have you noticed the bumps being itchy?
Lastly, red bumps/rash that appears over the body can be associated with Syphilis. There is not a lot of syphilis in the heterosexual population in Canada, but it is possible.
I would recommend going to see a medical professional about these symptoms. If it is something like Syphilis it’s important that both you and your partner get treated.
It can be difficult to navigate these symptoms, especially when you know your partner may have been at risk. The only way to know for sure is to get tested for STIs.
For these symptoms you can go to your regular doctor, a walk-in clinic, or an STI clinic. You can also get tested for STIs at the same places. If you need help finding an STI clinic near you check out our Clinic Finder tool.
Let us know if you have any other questions.