From a medical standpoint – I’ll chime in. Chronic ‘Hip Flexor Tendinitis’ is something that is often diagnosed but rarely exists, though it’s certainly not impossible given what you’re attempting. As a sport MD I’d want to assess your hip joint ROM, and see what manoeuvres recreate your pain; I’d also want to get some X-rays. These anterior hip pains can be due to other things such as hip impingement (femoroacetabular impingement), labral pathology or even OA (yes, even in young people). 2 questions: how old are you? Have you had xrays?
If you want to take this offline, email me: andy@evokeendurance.com