I have a sunken chest and I was wondering what do I do? I searched it up and it's called pectus excavatum (Photo)

Some information about pectus excavatum ( men and women) may be helpful…
Pectus Excavatum, also known as cobbler’s chest, sunken chest, funnel chest or simply a dent in the chest, is the most common congenital chest wall deformity, in which several ribs and the sternum grow abnormally. This produces a caved-in or sunken appearance of the anterior chest wall. Typically present at birth, this condition continues during the time of rapid bone growth and worsens until early teenage years. The severity of the defect and asymmetry of the chest widely vary. Pectus excavatum is often considered to be cosmetic, however it can impair cardiac and respiratory function, causing pain in the chest and back. People with the abnormality may experience negative psychosocial effects, and avoid activities that expose the chest.
For male patients, I have found that custom made solid pectoral implants made specifically for the area of depression is an option for a better cosmetic result.  In order to meet the needs of the specific patient, I meet with the patient to make the moulage for the custom silicone implant.
This preparation can take up to 1-2 hours to make and dry. The moulage is then sent to the company so that a solid silicone implant can be made from it to fit the patient. The specifics of the operation vary from patient to patient. During the consultation with the patient, I discuss the amount of augmentation that the patient desires. The preferred shape of the chest wall is also discussed with the patient. 
I hope this, and the attached link (demonstrating several cases), helps.

I use pec implants to correct the appearance of pectus excavatum often.  It is quite effective and patients are happy with results. Be sure to visit an experienced plastic surgeon with extensive experience in pectoral implants. 

Hello. From the looks of your photo, it does appear that you have the precuts excavatum.There are number of treatments for this, but none are really great in my opinion.Sometimes a small amount of fat can be transferred to soften the concavity, but has to be done conservatively, so that it is not just a squishy fatty area.  Since your precuts is located centrally,  I doubt the the pec implants would not camouflage this enough either.Good luck.