Slow oracle query being used in a tcl script - oracle

Question

I have written this query to be used by orasql and orafetch in a tcl script. The query is nested into a proc that is run as many times as a date range given needs it to be run (usually around 3 times per instance). The tables with $YYYYMM are full month tables consisting of about 13 million rows. The $advocate variable will pull about 39 different account_ids which will reduce the number of rows returned substantially but not great as great as claim_status_code='4' (~460,000 rows). I have no idea what the current run-time of the query is because I have no allowed it to run longer than about 30 mins. I really need this to pull in a couple of seconds, I am just way to new to all of this to know how to improve the speed. I have looked at oracle documentation over optimizing queries and I have tried incorporate those suggestions into what I have written. Any help at all would be much appreciated.
select
case
when clg_payor_id
is null
then payor_id1
else clg_payor_id
end
, count(unique era_id||invoice) count
from marge.e835_clp_$YYYYMM#e835v2
where claim_status_code='4' and payor_id1!='client'
group by case when clg_payor_id is null then payor_id1 else clg_payor_id end, era_id
having era_id
in (
select era_id
from marge.e835_checks_$YYYYMM#e835v2
where input_date between '$date1' and '$date2'
group by account_id, era_id
having account_id
in (
select ea.account_id
from cowboy.enrolled_submitters es
, cowboy.enrolled_accounts ea
where ea.submitter_id=es.submitter_id
and es.advocate='$advocate'
)
)
order by count desc
UPDATE: As suggested, I have moved the era_id out of the HAVING clause and into the WHERE. When I run this query, it returns a lot of unwanted results because of all of the account_id's but I can't figure out why. The query did actually run though and it only took ~9 secs. So much improved.
select
case
when clg_payor_id
is null
then payor_id1
else clg_payor_id
end
, account_id, count(unique era_id||invoice) count
from marge.e835_clp_$YYYYMM#e835v2
where claim_status_code='4'
and payor_id1!='client'
and era_id
in (
select era_id
from marge.e835_checks_$YYYYMM#e835v2
where input_date between '$date1' and '$date2'
group by account_id
, era_id
having account_id
in (
select ea.account_id
from cowboy.enrolled_submitters es
, cowboy.enrolled_accounts ea
where ea.submitter_id=es.submitter_id
and es.advocate='$advocate'
)
)
group by case when clg_payor_id is null then payor_id1 else clg_payor_id end, account_id
order by count desc