Nasty blood dots on the roof of my mouth

That could be an infection like Strep Throat. In case you are wondering, Strep throat is an infection in the throat and tonsils caused by group A Streptococcus bacteria (called “group A strep”). Group A strep bacteria can also live in a person’s nose and throat without causing illness. The bacteria spread through contact with droplets after the infected person coughs or sneezes. If you touch your mouth, nose, or eyes after touching something with these droplets on it, you may become ill. If you drink from the same glass or eat from the same plate as a sick person, you could also become ill. It is also possible to get strep throat from touching sores on the skin caused by group A strep.

Source: [b]https://www.cdc.gov/features/strepthroat/index[b].html

That could be an infection like Strep Throat. In case you are wondering, Strep throat is an infection in the throat and tonsils caused by group A Streptococcus bacteria (called “group A strep”). Group A strep bacteria can also live in a person’s nose and throat without causing illness. The bacteria spread through contact with droplets after the infected person coughs or sneezes. If you touch your mouth, nose, or eyes after touching something with these droplets on it, you may become ill. If you drink from the same glass or eat from the same plate as a sick person, you could also become ill. It is also possible to get strep throat from touching sores on the skin caused by group A strep.

As mianicole has said, it could be an infection. However it could also be a rash or reaction to something you ate. Either way you need to see a doctor about this.