It is hard to know what is causing you to develop these red spots after a massage. A massage on its own should not do this.
You could be having some sort of reaction to the massage oil that is being used. You may have sensitive skin that is irritated by these oils. This irritation can cause pores in the skin to plug which can lead to pimples. If this is the case, then you may want to try a different types of massage oil. Avoid those with any sort of smell or flavouring. You may also want to bring your own massage oil so that you know that it is not contaminated with any bacteria.
Showering following the massage will clear the skin of any extra oil that can also lead to blocked pores. This will wash away the oil as well as bacteria.
You can also request that the person giving you the massage wash their hands before starting the massage to remove any oils and bacteria from previous massages.
Please leave a comment to let us know if this answers your question or if you need more information.
For other readers, please feel free to leave a comment, or let us know if this was helpful.