Physiology of Decompresssion sickness FAQ

During a recent dive in the British Virgin Islands, I went to 94 feet. The dive shop could not hook up our computers to our regulators, so we dived according to the divemaster’s computer. I have no record of the dive besides written notes. Approximately 12 hours later the second joint of my little finger has swollen slightly. Could this be decompression illness? I have a flight scheduled in two days. 
Diagnosis via email is impossible; your best bet is an evaluation by a physician. The following are possibilities based on your account and the physiology of decompression sickness (DCS).
The list of likely explanations for swelling in a finger includes mechanical injury and contact with marine life. In the absence of other neurological symptoms, DCS does not typically present with isolated swelling in a small joint such as a finger or toe. As in above-water activities, fingers are susceptible to a wide range of mechanical injuries in diving. Actions while diving include holding onto a boat for support, getting rope burns, carrying gear, climbing boat ladders and maneuvering a bulky camera or other equipment. Any of these actions can involve twisting or jamming forces.
Another possible explanation for the inflammation would be contact with marine organisms. Dive operations frequently use permanently established mooring lines to avoid dragging anchors across fragile reefs. While this helps protect the reef, that mooring line also becomes a site for colonization by marine animals such as hydroids, which, like their jellyfish relatives, have stinging cells (nematocysts). A diver who uses a mooring line to control descent or ascent may unintentionally brush his or her fingers across the nematocysts, causing swelling, redness and possibly blisters to the affected hand.
Treatment for contact with nematocysts includes applying vinegar shortly after exiting the water and thoroughly rinsing with seawater to remove any remaining stinging cells. Subsequent care includes using topical steroids (cortisone) or analgesics (ibuprofen) if needed and soaking in hot water.
Treatment for a dive-related mechanical injury would be no different than for an above-water injury. Support, wrap or splint the joint as necessary to protect it. Analgesics such as acetaminophen or ibuprofen may provide relief. Applying ice to a joint may relieve swelling.
If the finger is protected from further harm from actions such as carrying luggage, flying is not a concern. As with any injury, medical evaluation is always appropriate and recommended, especially if function is impaired in the hand. The physician does not need to be familiar with dive medicine. Appropriate injury evaluation and care is within the capabilities of any physician.
— Frances Smith, EMT-P, DMT