Before I say anything I want to advise that you go to the hospital or atleast a walk in clinic. If you are experiencing increasing numbness and swelling after 24 hours that is a very bad sign. For all you know you have a staff infection in your blood and your body is barely fighting it right now..tomorrow you might wake up and your arm has made a quick turn for the worst and when you get to the ER you are going to hear the word amputation. Seriously, be logical, if your concern is enough that you would create a username on a forum, make a post, take pictures, it is obviously serious. Don't you think that warrants going to a doctor?
Did the swelling and numbing you mention start instantly? Did the swelling/burning/numbness feel like it traveled away from the injection site? For example if you inject in the crook of your elbow and instantaneously as you are pushing the syringe the pain/swelling/etc. traveled down your arm and your hand was to become swollen. What I just described is how you would react to pushign even a single unit into an artery. At first I thought that might be the case, but to inject 60 units you would have experience severe pain while pushing the plunger. But from what you describe it sounds more like a missed shot.. the swelling took a few minutes to start up and is localized to your injection site. Numbness can be related to the swelling or trauma you caused to nervesd. a red mark the size of a cd is pretty serious though man
What you were shooting? Was it methadone pills or methadone syrup? I have a feeling it was pills because 60 units of syrup from a clinic would probably be barely anything. So assuming it was pills what was it filtered with(i.e. cotton, a micron filter, or no filter). You do have reason to be concerned man.. you only have one body and you cant buy body parts at Walmart.... I have missed a fwe shots in my day.. even a shot that siez filled with blood and I have never had anything more than moderate swelling..barely even visible along with minor pain at the injection site (only if I put pressure on it not when i am just sitting).
I am going to warn you that if you injected methadone pills and did not use a micron filter you are likely forming an abscess. You describe a lump under your skin. Dude just typing this reply I am wondering why your concern was not enough to get you to a doctor? Either way, you have no choice at this point now that a lump is forming under your skin. You need antibiotics for an abscess and also you might need the doctor to lance it.
On top of that you are experiencing sporadic discoloring/bruising and increases in pain/numbing in your whole arm....AND now your heart is giving you reason for concern? What will it take for you to see a doctor? Does the pain/visible symptoms have to become so severe your concerned you are going to die or something? Sorry I am being a dick but it blows my mind that people will put their limbs/life at risk because they are scared the doctors going to give them the death penalty because you are an IV drug user..or you don't wanna spend the money. Also the heartburn like feeling you describe in your heart you compare to a feeling you get when you inject dope and get a rush. You should not be having pain in your heart. That is scary.
Take a look at the iv complications thread. Once sepsis sets in (and god only knows what bacteria is brweing in your body) another 24-48 hours might go by and the pain might not even be unbearable...and when the doc finally sees you he'll be preparing his bone saw.