Last week I felt a small hard pea sized lump in my groin. It’s still there a week later but slightly bigger, not sure if it’s a spot under the skin?

Lymph node. What you described suggests a slightly enlarged lymph node/gland due to some inflammation in your lower limb. You may feel the node every couple of weeks, if the lymph gland doubles in size, becomes painful, ulcerates, or other nodes become enlarged, or you develop fever, or lose weight, you should see a doctor.
Wish you good health! - Have a diet rich in fresh vegetables, fruits, whole grains, milk and milk products, nuts, beans, legumes, lentils and small amounts of lean meats. Avoid saturated fats. Drink enough water daily, so that your urine is mostly colorless. Exercise at least 150 minutes/week and increase the intensity of exercise gradually. Do not use tobacco, alcohol, weed or street drugs in any form.
Practice safe sex, if you have sex.