If you are concerned that you may have caught an STD from a person you recently had unprotected sex with, and you are in one of these situations, you should consider using an STD home testing kit.
You're too embarrassed to have the STD tests done in person at a clinic
Even though STDS are very common and contracting one does not mean that a person has done anything wrong, many people who suspect that they have STDS feel too ashamed to go to their local clinics to get tested. If you have been putting off getting an STD test for this reason and are concerned about the health implications of delaying the treatment for the STD you think you may have, you should use a home testing kit.
This kit provides you with the materials you need to give a sample, which you can then package up and post to a laboratory, who will test your sample for signs of specific, common STDs before sending you your results. If you are found to have an STD, you can then take whichever actions are necessary (such as going on a course of antibiotics or using a topical ointment) to clear the infection or manage the symptoms.
This kit will enable you to determine if you have an STD without having to experience the embarrassment of going into an STD clinic, where you would not only need to discuss your sexual history in person with the clinic's nurses or doctors but would also have to run the risk of bumping into someone you know in the clinic's waiting room or car park.
You are self-isolating and don't want to risk going to your GP in person
If the pandemic has resulted in you having to self-isolate, and you are worried you have an STD, then it might be more responsible to use a home testing kit instead of visiting your GP or an STD clinic in person. This would enable you to find out if you have a particular STD without travelling to a clinic in person.
If you decide to use the kit for this reason, you may want to notify the lab to which you'll be sending the kit of the fact that you're self-isolating, as they can then take any extra precautions they feel are necessary. For example, they may sanitise the outer packaging that contains your sample before removing and testing it.