There are two separate problems that can be ascertained from your question: one is razor bumps while the other is a problem of skin irritation after shaving. Razor bumps are usually an inevitable part of regular shaving that people have to contend with. The remedy for this problem is to simply stop shaving for some time and alter your shaving schedule a bit. For the skin irritation after shaving, you need to adopt some of the methods used by men as part of their post-shave skin care regimen. Since you are shaving an area that is not usually left open, you must remember that improper skin care can lead to a problem of infection that can cause pimple like growths. These can be quite irritating to contend with and take time to go away. Not to mention that they will look much worse than the rash that you already have.
Razor bumps are a problem that occurs when the hair that has just been cut curls as it grows and then takes a u-turn to start growing back into the skin. In another case, the hair will end up growing sideways into the skin and then start to curl. In both cases, the problem causes a lot of irritation and sometimes pain from the resulting inflammation. This is a problem that happens very regularly in men and the way to deal with the problem is to immediately shave and then locate the errant hair. Once located, you can use a sharp pointy object like a tooth pick and lift the hair out of the skin. This will immediately alleviate all the pain though a pimple like formation will remain and go away after a while. The best way to avoid this situation is to shave with and against the grain, so that the hair growth is then not biased in a single direction. Additionally, you also need to shave after the hair is given some time to grow. Another solution is to switch from a double or triple blade razor to a single blade razor that does not cut the hair too deeply in the skin.
For the rash that you are facing, there are many creams that are mixed with an antiseptic solution. Find one that contains aloe vera and you will never have to face a situation of rash ever again. There are some popular brands of after shave gels that do contain aloe vera, so buy these – even if it is a men’s product.