Stuck in a hard place

For those of you that paid for a Nexus, who did you use? I got denied on rhinitis and sinusitis. I have decades of records. TERA was conceded by the VA, but the C&P examiner opined less likely than not. I'm not a PACT ACT veteran so it isn't presumptive. I don't have STR's but I do have deck logs showing significant exposure. My PCP said she would sign a Nexus for me but backed out last minute. go figure. So, I need to find a reputable company that will help me get that Nexus and argue the negative opine. who did you use? did it help? I could have my wife write a Nexus, but it has less probative value. Thanks in advance.