Hi VT, I was in a similar boat as a DO at an ACGME community program and matched into A/I. A/I is competitive and it will be harder matching as a DO from a community program, but definitely possible!
I would strongly recommend for you to focus on getting an abstract and poster presented at the AAAAI national meeting. The abstract submission deadline for the 2019 meeting is August 30 ( a little over a week from now), so you will have to hurry! But I would strongly recommend this. Presenting at the AAAAI is one of the most important things you can do to show your interest in the specialty. For the upcoming deadline, you just need an abstract submitted. You can do a case report.
Abstract Submission | AAAAI Annual Meeting
Other than the AAAAI national meeting, there is also the ACAAI national meeting which is good to present at. However, the deadline for the ACAAI has already passed. You can do next year's.
If there are any AI docs at your institution, I would try to talk to them and get a rotation in A/I to see if you like it. If you are able to do any A/I related research, that would be highly recommended. If the A/I docs at your place are not doing research, but a doc in another specialty is (for example, a Dermatologist doing Atopic Dermatitis research, or an ENT doing sinusitis research, or a Pulmonologist doing asthma research), then do research with them.
Right now, get your AAAAI abstract submitted before the deadline. You won't get another chance until next year if you miss this one.