Brief Answer:
regarding ED

Detailed Answer:
Hi...
Welcome to 'Ask a doctor' service.
I am Dr Ajeet XXXXXXX

There are multiple reasons for erectile dysfunction like heart disease, diabetes but what I can make out from your symptoms is that it is probably not a major issue in your case.

You had a major illness in the form of typhoid and malaria which has caused fatigue and have depleted your energy stores and micronutrients.

The first phase of a sexual act is an exciting phase which is an emotional response.
As you were in convalescence state, there was no proper communication between your brain and reproductive organs thus causing improper filling and erection.
This lead to stress and performance anxiety which further deteriorated the performance.
A vicious cycle starts in which low self-esteem also contributes.

Ideally, you should abstain from the sexual activity for a few days till you recover your energy and mindset.
This can also take your partner into confidence.
Please dno't be overstressed.

Go for counseling if required, which will lower your anxiety and stress related to sex.
Be physically active.
Quit smoking and alcohol (if at all do).

Follow a healthy and nourishing diet with a nourishing diet with plentiful fruits and vegetables.
Take protein supplements.
L arginine is a protein amino acid which produces nitric oxide, involved in the relaxation of blood vessels causing penile engorgement.

Till the time you recover, you can intermittently take Sildenafil 50mg around half an hour before the act. It acts by relaxing smooth muscles and increasing blood flow in the penis during sexual stimulation. As this drug may have contraindications and side effects so better if taken under medical supervision. Peak effect occurs in 2 hours and stays for about 4 hours. It's effectiveness decreases after a fatty meal.

You should improve with the course of time.

Hope that I have answered your query.
If you have any doubts, please let me know.

Regards.

---