I have chest soreness and radiating pain.Is this due to pleurisy or costochondritis?

Hello doctor,

• I am a 36 year old, otherwise healthy (as far as I know) female.

• I was a smoker earlier. No history of heart disease.

• My mother has COPD, but has been a long time smoker. 

• Two and a half weeks ago, I went on a hayride with my sons.

• I have a short stature. To get on and off the hayride, I literally had to pull myself up onto the trailer. (Imagine pulling yourself out of a swimming pool).

• The next morning, I woke up with chest soreness.

• I had pain in the upper left chest area, a few inches to the left of sternum.

• That was a radiating pain over the breast towards armpit.

• Pain worsened on bending over.

• Also, I could locate very tender spots when pressing on the area with fingers.

• I had no pain during regular breathing, but very deep breaths caused pain to worsen (from the left of sternum radiating across and to the left breast). 

• Over the past two and a half weeks, pain has improved, but still not completely subsided.

• Most of the pain (while bending) is gone, but I still have tender areas across upper left chest when poking around with finger (trigger points?).

• I have some minor discomfort on taking deep breath, but greatly improved from what it was.

• And now pain is just in an area to the left of my left breast.

• Now, pain is mostly towards armpit area and may be slightly radiating to the upper, bottom side of arm.

• I do not have much pain as it was in the beginning, but more of soreness.

• It is not constant, it occurs mostly just when I move in a certain way or tense my chest.

• Also I am noticing upper left back discomfort, not really pain. 

• Local FNP suspects strained muscle. No x-rays were done.

• I have no cough, no shortness of breath, no loss of appetite, no indigestion or heartburn.

• Otherwise I feel fine. My concern is that I still have some pain and discomfort after almost 3 weeks.

• Shouldn't a muscle strain be healed by now?

• I am a bit concerned as it may be something more serious than a strained muscle, perhaps pleurisy or costochondritis?